The use of active oxygen sources (e.g. peroxide) with a transition metal catalyst is known to improve bleaching performance; see for example U.S. Pat. No. 5,246,612. Similarly, use of bleach activating agents with oxygen sources (e.g. percarbonates) are known to generate bleaching compositions at a point of use. However, the delivery of these reactive components—active oxygen sources and activator materials—in a single bleaching formulation suffers from numerous stability challenges. In particular, the components react when mixed together. Moreover, certain bleach activating agents when combined with active oxygen sources have poor available oxygen stability over time, especially at elevated storage temperatures.
Improvements to stability, as well as separating the active components to prevent premature generation of bleaching compositions have been disclosed for various bleach activating technologies. For example, the use of coatings or encapsulation of particulate materials, including the bleach activator TAED have been employed (U.S. Pat. No. 4,853,143). Moreover, the improvement in stability of bleach compositions has also included, for example, development of agglomerated forms or granules and encapsulating the same (EP 1735422), use of water soluble ligands or complexing agents (e.g. EDTA, DTPA, NTA, and alkaline metal and alkaline earth metal salts, alkaline metal tryphosphates), and/or use of biopolymers and polysaccharides to stabilize catalysts. Despite these improvements, stability concerns remain for formulating solid and/or multi-use detergent compositions containing such reactive components.
The use of bleach activating agents or catalysts with unstable oxygen sources results in limited shipment and/or storage shelf life or stability despite the various advances by those skilled in the art. The shelf life is commonly regarded as the period of time over which the product may be stored while retaining its required performance efficacy. A satisfactory shelf life is in many instances a crucial factor for the success of a commercial product. A product with a short shelf life generally dictates that the product is made in small batches and is rapidly sold to the consumer. Beneficially, products with a longer shelf life may be made in larger batches, maintained in storage for a longer period of time and/or maintained by a consumer for a longer period of time before use. There remains a clear need to increase the shelf life of a combination product containing an oxidant and a bleach activator to prevent the reaction of the active components.
Accordingly, it is an objective of the claimed invention to develop solid compositions having increased shelf life and stability when employing reactive components, such as a peroxygen source (e.g. sodium percarbonate) and a bleach activator (e.g. TAED) without requiring any encapsulation, layering of components or the like to provide physical separation of the reactive components in a solid formulation.
It is an object of the present invention to formulate solid compositions with improved stability by minimizing the interaction between reactive components, such as coatings and/or binding systems to minimize the interaction between the reactive components, such as a peroxygen source (e.g. sodium percarbonate) and a bleach activator (e.g. TAED).
A further object of the invention is to incorporate an active oxygen source and a bleach activating agent into a single solid detergent block suitable for multi-dispensing over periods of time up to 2 weeks, while beneficially overcoming the poor available oxygen stability as experienced in the prior art, including at elevated storage temperatures.
A further object of the invention is to provide methods of protection and/or formulating a bleach activator and oxygen source in a single, stabilized solid detergent block with a sequestrant and an anionic surfactant binding agent to prevent reaction of the bleach activating agent an active oxygen source (e.g. peroxygen source).
Other objects, advantages and features of the present invention will become apparent from the following specification taken in conjunction with the accompanying drawings.